Lead free steel and method of manufacturing

ABSTRACT

An essentially lead free steel having, in percent by weight (wt-%): Carbon: 0.39-0.43%; Manganese: 0.75-1.00%; Silicon: 0.15-0.35%; Chromium: 0.80-1.05%; Molybdenum: 0.15-0.25%; at least one of Tellurium: 0.003-0.090 wt-%, Selenium: 0.080-0.2 wt-%, Sulfur: 0.065-0.09% wt-%, and Bismuth: 0.03-0.1 wt-%; and the balance being Fe and normally occurring scrap steel impurities. A method for manufacturing an essentially lead free steel by subjecting a hot-rolled steel product to a heat treatment in which the steel product is subjected to a first temperature for a first duration; the steel product is subjected to a second temperature for a second duration, wherein the second temperature is less than the first temperature; and the steel product is subjected to a third temperature for a third time period, wherein the third temperature is greater than the second temperature; and cooling the steel product. After the heat treatment the steel is cold worked to the desired size.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present application for a patent claims priority to U.S. ProvisionalPatent Application Ser. No. 62/162,384 entitled “Lead Free Steel andMethod of Manufacturing” filed on May 15, 2015 and assigned to theassignees hereof and hereby expressly incorporated by reference herein.

FIELD

The present disclosure relates to a steel product with a particularsteel composition and method of making the steel product using aspecific heat treatment process, one or more of which results in thedesired properties of the steel product. Additionally, the presentinvention relates to a steel product that is essentially free or free oflead, obtainable from scrap steel, having good hardenability,machinability and wear resistance for use as fasteners, hose fittings,shafts, or other like machined components.

BACKGROUND

Free-cutting steels commonly used today often contain lead, which is aneffective element for providing machinability. Exemplary lead containingfree-cutting steel typically contains 0.2% by weight of lead (Pb), or arange of lead from 0.15% to 0.35%, along with other elements. Forexample, steel containing lead, such as steel commonly referred to as41L40 made according to ASTM A-322-91, improves machinability of thesteel without sacrificing other desirable properties. These leadcontaining steels have very good machinability, wear resistance,hardenability, and dimensional stability, and also result in prolongedtool life for the tools that are used to machine the steel, desiredmachining speeds, desired machining feed rates, and machiningproductivity during manufacturing of machined components made from thesetypes of lead containing steels. However, lead is a hazardous elementfor the environment and people. As such, these lead containing steelsare not environmentally friendly or safe to make and/or use. Forinstance, in some regions manufacturing lead containing steels isprohibited, and as a result lead containing steels are often purchasedoutside of these regions in order to manufacture the desired machinedcomponents. In some regions steel containing lead may not even beutilized to make components, regardless of the origin of the steel.

SUMMARY

Some aspects of the invention is a steel composition, which in somecases is free of or substantially free of lead (Pb). In some aspects ofthe invention, a steel composition, such as a composition that is freeof or substantially free of lead (Pb), may be manufactured using aparticular heat treatment, such as a particular annealing process. Insome aspects of the invention, the steel composition provided is areplacement for 41L40 steel, or other like steels. The presentlydisclosed composition provides a steel product with improvedmachinability that can be used in a wide range of machined components,including but not limited to fasteners, hose fittings, shafts, drillcollars, couplings, axles, gears, valves, pins, wedges, steeringassembly components, die rolls, spindles, or the like.

In some aspects of the invention, the following elements are present inthe steel products: carbon in an amount by weight of 0.39-0.43%;Manganese in an amount by weight of 0.75-1.00%; Silicon in an amount byweight of 0.15-0.35%; Chromium in an amount by weight of 0.80-1.05%; andMolybdenum in an amount by weight of 0.15-0.25%. Additionally, in someaspects of the invention, the steel products may include the addition ofanother element, or combinations of multiple elements, that will improvethe machinability, such as but not limited to at least one of tellurium(Te), selenium (Se), sulfur (S), bismuth (Bi), and/or other likeelements. In other aspects of the invention, the presently disclosedsteel composition may comprise increasing the amount of one or more ofthese elements that may already be used in currently produced steels, orincreasing the amount of combinations of these elements, such aselevating the levels of tellurium (Te), selenium (Se), sulfur (S),bismuth (Bi), or other like elements in these types of steels. In stillother aspects of the invention, the amount of tellurium (Te), selenium(Se), sulfur (S), bismuth (Bi), or the like used in the steel may bemore finely tuned in order to achieve the desired properties.

Tellurium, in some aspects, may be added to, and/or controlled within,the steel to a range of 0.001 to 0.12 wt-%, and preferably in a range of0.003-0.090 wt-%.

Selenium, in some aspects, may be added to, and/or controlled within,the steel to a range of 0.05 to 0.25 wt-%, and preferably in a range of0.08 to 0.2 wt-%.

Sulfur, in some aspects, may be added to, and/or controlled within, thesteel to a range of 0.05-0.1 wt-% within the steel. In other aspects,the sulfur may be added to, and/or controlled within, the steel to arange of 0.06-0.1% wt-%. In other aspects, the sulfur may be added to,and/or controlled within, the steel to a range of 0.065-0.09% wt-%.These amounts of sulfur are different than the sulfur content of leadedsteels, such as 41L40 steels which typically have lead in a range of0.15-0.35 wt-%. Some leaded steels may have no sulfur, or sulfur atlevels much lower than the levels described herein.

Bismuth, in some aspects of the invention, may be added to, and/orcontrolled within, the steel to a range of 0.001 to 0.12 wt-%, andpreferably in a range of 0.03 to 0.1 wt-%.

In some aspects of the invention, the typical residuals that may befound in scrap steel may be found in the steel described herein. In someaspects of the invention the following elements may be present as atypical residual or may be intentionally added and/or held to thefollowing ranges: copper up to a maximum of 0.50 weight percent (and insome aspects of the invention copper may be limited to a maximum of 0.1%wt-%); calcium up to a maximum of 20 ppm; boron up to a maximum of 10ppm; and nitrogen in a range of 50 to 150 ppm. In other aspects of theinvention, these additional elements, or other elements, may be held todifferent levels in accordance with various aspects of the invention, asdescribed throughout.

In some aspects of the invention, the presently disclosed composition isprepared from scrap steel where all or substantially all but traceamounts of lead is removed. In such processes scrap steel is supplied toa furnace (e.g., an electric arc furnace or “EAF”) in one or morecharges and melted. The alloying elements are added or controlled withinthe furnace or within subsequent processing steps (e.g., in a ladle, orthe like). The steel products discussed herein may be formed by strandcasting or ingot casting molten steel in a hot forming process into abillet, and subsequently hot rolling the steel products. In some aspectsof the invention, the cast billets may be directly hot rolled aftercasting. Alternatively, the cast billets may be cooled, which may occurat a controlled rate in order to prevent the formation of imperfectionscaused by cooling that is too rapid. If cooled, the cast billets will bereheated to a prescribed temperature and reduced in a hot rollingprocess, and/or potentially a cold rolling process. The steel productmay then be subjected to a heat treatment and thereafter cold worked(e.g., cold drawn, cold extruded, and/or cold rolled) to a finished sizeinto a final steel product suitable for machining into a machinedcomponent.

The steel products of the present disclosure can also be formed in ablast furnace or other furnace in which the composition of the finishedsteel can be controlled and a heat treatment can be applied.

Regardless of how the steel product is formed, special care may be givento heating and cooling the steel product during a heat treatment, suchas annealing, to ensure proper microstructure and mechanical propertiesof the final product. In some aspects of the invention, an annealingprocess is utilized where the product is heated for a predetermined timeunder particular conditions in one or more steps, subjected to coolingfor a predetermined time under particular conditions in one or moresteps, then reheated for a predetermined time under particularconditions in one or more steps (e.g., a temperature spike, or thelike), and finally, subjected to cooling for a predetermined time underparticular conditions in one or more steps. The heating and/or coolingduring the one or more heat treatment steps may or may not be performedusing a non-ambient atmosphere.

With respect to the composition of the steel in the present invention,in some aspects of the invention, the addition of, or increase in theamount of, at least one or more of Te, Se, S, Bi, and/or other likeelements may result in a more adherent scaling after the steel productis formed. The temperature spike (e.g., the increased temperature afterthe first heating and first cooling) in the presently disclosedannealing process permits removal of the scale more easily in downstreamprocessing when compared to similar steels subjected to a heat treatmentwithout the temperature spike described herein.

In some aspects of the invention, the presently disclosed steelcomposition, after being subjected to the present heat treatment (e.g.,annealing process, or the like), results in a product with a hardness ofabout 100-225 Brinell Hardness (55-97 Rockwell B). In some aspects ofthe invention, the presently disclosed steel composition, after beingsubjected to the present heat treatment provides for a hardness of about125-210 Brinell Hardness (70-95 Rockwell B).

In some aspects of the invention, the presently disclosed steelcomposition, after being subjected to the present heat treatment and oneor more of cold drawing, cold rolling, and/or extrusion, results in aproduct with a hardness of about 125-300 Brinell Hardness (70 Rockwell Bto 32 Rockwell C). In some aspects of the invention, the presentlydisclosed steel composition, after being subjected to the present heattreatment and one or more of cold drawing, cold rolling, and/orextrusion provides for a hardness of about 150-260 Brinell Hardness (80Rockwell B-26 Rockwell C).

In some aspects of the invention, the presently disclosed steelcomposition after being subjected to the presently disclosed heattreatment (and other potential processing steps) provides for amachinability rating of greater than about 70%, greater than about 75%,greater than about 80%, or greater than about 85% (e.g., up to about 86%or greater than about 86%) of an AISI 1212 steel that provides thebaseline for machinability (e.g., a steel with 100% machinabilityrating).

Aspects of the invention comprise a steel product that is essentiallylead free. The steel product composition comprises: carbon in a range of0.2 to 0.6 wt-%; manganese in a range of 0.6 to 1.1 wt-%; silicon in arange of 0.1 to 0.4 wt-%; chromium in a range of 0.6 to 1.2 wt-%;molybdenum in a range of 0.1 to 0.3 wt-%; at least one or more of:tellurium in a range of 0.001 to 0.12 wt-%; selenium in a range of 0.05to 0.25 wt-%; sulfur in a range of 0.4 to 0.12 wt-%; or bismuth in arange of 0.01 to 0.15 wt-%; and balance being Fe and normally occurringscrap steel impurities. The steel product is subjected to a heattreatment process during which the steel product is subjected to: afirst temperature for a first duration; a second temperature for asecond duration, wherein the second temperature is less than the firsttemperature; and a third temperature for a for a third time period,wherein the third temperature is greater than the second temperature.The steel product is cooled after being subjected to the thirdtemperature during the heat treatment.

In further accord with the invention, the composition of the steelproduct comprises only the tellurium, and wherein the tellurium is in arange of 0.003 to 0.090 wt-%.

In another aspect of the invention, the composition of the steel productcomprises only the selenium, and wherein the selenium is in a range of0.080 to 0.20 wt-%.

In still another aspect of the invention, the composition of the steelproduct comprises only the sulfur, and wherein the sulfur is in a rangeof 0.065 to 0.090 wt-%.

In yet another aspect of the invention, the composition of the steelproduct comprises only the bismuth, and wherein the bismuth is in arange of 0.03 to 0.1 wt-%.

In further accord with the invention, at the first temperature the steelproduct is in an austenitic phase, and at the second temperature and thethird temperature the steel product is in a pearlitic/ferritic phase.

In another aspect of the invention, the first temperature ranges between1500-1800 degrees F., the second temperature ranges between 1000-1300degrees F., and the third temperature ranges between 1100-1400 degreesF.

In still another aspect of the invention, the first temperature rangesbetween 1590-1690 degrees F., the second temperature ranges between1100-1200 degrees F., and the third temperature ranges between 1200-1300degrees F.

In yet another aspect of the invention, the microstructure of the steelproduct comprises lamellar perlite.

In further accord with an aspect of the invention, the microstructure ofthe steel product comprises at least 75% lamellar perlite.

Aspects of the invention comprise a method for manufacturing anessentially lead free steel. The method comprises subjecting a hotrolled steel product to a heat treatment. Within the heat treatment thesteel product is subjected to a first temperature for a first duration.Then the steel product is subjected to a second temperature for a secondduration, wherein the second temperature is less than the firsttemperature. Then the steel product is subjected to a third temperaturefor a third time period, wherein the third temperature is greater thanthe second temperature. The steel product is then subjected to coolingafter heat treatment. The steel product has a composition thatcomprises: carbon in a range of 0.2 to 0.6 wt-%; manganese in a range of0.6 to 1.1 wt-%; silicon in a range of 0.1 to 0.4 wt-%; chromium in arange of 0.6 to 1.2 wt-%; molybdenum in a range of 0.1 to 0.3 wt-%; andat least one or more of: tellurium in a range of 0.001 to 0.12 wt-%;selenium in a range of 0.05 to 0.25 wt-%; sulfur in a range of 0.4 to0.12 wt-%; or bismuth in a range of 0.01 to 0.15 wt-%; and the balancebeing Fe and normally occurring scrap steel impurities.

In further accord with an aspect of the invention, the compositioncomprises only the tellurium, and wherein the tellurium is in a range of0.003 to 0.090 wt-%.

In still another aspect of the invention, the composition comprises onlythe selenium, and wherein the selenium is in a range of 0.080 to 0.20wt-%.

In yet another aspect of the invention, the composition comprises onlythe sulfur, and wherein the sulfur is in a range of 0.065 to 0.090 wt-%.

In further accord with an aspect of the invention, the compositioncomprises only the bismuth, and wherein the bismuth is in a range of0.03 to 0.1 wt-%.

In another aspect of the invention, at the first temperature the steelproduct is in an austenitic phase, and at the second temperature and thethird temperature the steel product is in a pearlitic/ferritic phase andthe third temperature is greater than the second temperature.

In still another aspect of the invention, the first temperature rangesbetween 1500-1800 degrees F., the second temperature ranges between1000-1300 degrees F., and the third temperature ranges between 1100-1400degrees F.

In yet another aspect of the invention, the first temperature rangesbetween 1590-1690 degrees F., the second temperature ranges between1100-1200 degrees F., and the third temperature ranges between 1200-1300degrees F.

In further accord with an aspect of the invention, the microstructure ofthe steel product comprises lamellar perlite.

In another aspect of the invention, the microstructure comprises atleast 75% lamellar perlite.

Aspects of the invention comprise a steel product that is essentiallylead free. The steel product comprises: carbon in a range of 0.2 to 0.6wt-%; manganese in a range of 0.6 to 1.1 wt-%; silicon in a range of 0.1to 0.4 wt-%; chromium in a range of 0.6 to 1.2 wt-%; molybdenum in arange of 0.1 to 0.3 wt-%; at least one or more of: tellurium in a rangeof 0.001 to 0.12 wt-%; selenium in a range of 0.05 to 0.25 wt-%; sulfurin a range of 0.4 to 0.12 wt-%; or bismuth in a range of 0.01 to 0.15wt-%; and the balance being Fe and normally occurring scrap steelimpurities.

Aspects of the invention comprise a method for a heat treatment process.The method comprises subjecting a hot rolled steel product to a heattreatment. Within the heat treatment the steel product is subjected to afirst temperature for a first duration, wherein the first temperatureranges between 1500-1800 degrees F. Then the steel product is subjectedto a second temperature for a second duration, wherein the secondtemperature ranges between 1000-1300 degrees F., and wherein the secondtemperature is less than the first temperature. Then the steel productis subjected to a third temperature for a third time period, wherein thethird temperature ranges between 1100-1400 degrees F., and wherein thethird temperature is greater than the second temperature. After the heattreatment the steel is subjected to a cooling.

To the accomplishment of the foregoing and the related ends, the one ormore aspects of the invention comprise the features hereinafter fullydescribed and particularly pointed out in the claims. The followingdescription and the annexed drawings set forth certain illustrativefeatures of the one or more aspects of the invention. These features areindicative, however, of but a few of the various ways in which theprinciples of various aspects of the invention may be employed, and thisdescription is intended to include all such aspects and theirequivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described aspects of the invention in general terms,reference will be made to the accompanying drawings, where:

FIG. 1 illustrates a process flow for the manufacture of the steelproducts disclosed herein, in accordance with aspects of the presentdisclosure.

FIG. 2 illustrates the microstructure of a longitudinal cut sample takennear the core of a bar steel product disclosed herein, in accordancewith aspects of the present disclosure.

FIG. 3 illustrates the microstructure of a longitudinal cut sample takennear the surface of a bar steel product disclosed herein, in accordancewith aspects of the present disclosure.

FIG. 4 illustrates the microstructure of a transverse cut sample takennear the core of a bar steel product disclosed herein, in accordancewith aspects of the present disclosure.

FIG. 5 illustrates the microstructure of a transverse cut sample takennear the surface of a bar steel product disclosed herein, in accordancewith aspects of the present disclosure.

DETAILED DESCRIPTION

The present disclosure is generally related to manufacturing steelproducts that have the desired machinability and other propertieswithout utilizing additions of lead. Lead is, or may become, prohibitedor limited in its use as an alloying material in steel or as a componentof steel used to manufacture machined components. The present inventionprovides environmentally friendly and non-toxic steels that arenon-hazardous for persons in close proximity with the steels duringmanufacturing, machining, recycling and subsequent use, especiallyduring melting, hot working, or machining of the steels. The steels ofthe present invention achieve the desired properties without the use oflead based on the steel composition, heat treatment, and/or otherfactors, which are described in detail herein. Unlike the steels of thepresent invention, the currently available lead-free free-cutting steelsdo not provide properties that are satisfactory and in line with thesteels that utilize lead.

The invention described herein provides alternative lead-free orsubstantially lead-free steel products, and processes of manufacturingsuch steel products, which is not detrimental to the environment orunsafe for persons that come in contact with the steels duringmanufacture, machining into machined components, or ultimate use of thecomponents, but which also meet the material properties of leadedsteels, such as the properties of 41L40 steel, or other like steels.

FIG. 1 illustrates a general process for manufacturing steel products ofthe present disclosure. As illustrated by block 10 in FIG. 1 moltensteel is formed through the use of a blast finance, an electric arcfurnace (“EAF”), or other like furnace. Specifically with respect toprocessing within an EAF, materials such as scrap steel, iron ore, ordirect reduced iron may be melted into molten steel within the EAF. Asillustrated by block 20, alloys may be added to produce the desiredcomposition of the steel product (as will be discussed in further detaillater). The alloys may be added or controlled to some degree in the EAFor other furnace, in the ladle, or in other equipment during theprocessing of the steel.

As illustrated in block 30 of FIG. 1 the molten steel is transferredfrom the furnace to a ladle. Thereafter, the molten steel in the ladlemay be transferred to a tundish, and thereafter cast into billets, asillustrated by block 40. After being cast, the billet may be cooled andthereafter reheated in a reheating furnace, as illustrated by block 50in FIG. 1. In some aspects of the invention, after casting the billetsmay be sent to a tunnel furnace to maintain the desired temperaturebefore being sent for hot rolling or may be sent directly for hotrolling. In still other aspects of the invention the steel may becontinuously cast into the steel product and thereafter sent for furtherprocessing.

As illustrated by block 60 in FIG. 1, the billets are hot rolled intothe bars or other steel products in one or more hot rolling passesthrough one or more sets of dies. In some aspects of the invention, asillustrated by block 70, one or more cold rolling processes may beperformed on the bar or other steel products after hot rolling andbefore the heat treatment. Thereafter, as illustrated by block 80 thebars or other steel products are subjected to a heat treatment (e.g.,annealing process) in accordance with the heat treatment disclosedherein. In some aspects of the heat treatment, the steel product isheated to a first temperature, allowed to cool to a second temperaturebelow the first temperature, heated to a third temperature between thefirst temperature and the second temperature (e.g., using a temperaturespike), and thereafter allowed to cool. Each of the heat treatment stepsdescribed above may occur in one or more sub-steps and/orsub-temperatures.

As illustrated by block 90, after the heat treatment the steel productsmay be cold worked, for example, through a cold drawn, cold extrusion,or cold rolling process, into the desired final steel product, which canthen be machined, formed, or otherwise processed into the desiredcomponents, such as machined components.

The composition of the steel in the present disclosure includeselements, such as tellurium, selenium, sulfur, bismuth, and/or otherlike, which are added to, or controlled within, the steel composition.Alternatively, if one or more of these elements currently exist in asteel composition, the amount of one or more of these elements may beincreased to levels higher than the ordinary levels of these elements.In either case, for steels having lead, with the addition, and/or theincreased amount, of tellurium, selenium, sulfur, bismuth, and/or otherlike elements in the steel, the purposeful addition of lead iseliminated (e.g., with the exception of trace elements of lead that maybe found in scrap steel, or the like). Additionally, the specific heattreatment process described herein includes annealing steel made fromthe composition to temperatures in which the steel product is in anaustenitic phase, cooling the steel product to a temperature at which itis below an austenitic phase (e.g., pearlitic/ferritic phase), heatingthe steel product back up to a temperature at which the steel productremains in the pearlitic/ferritic phase (e.g., a rapid temperaturespike), and cooling the steel product thereafter (e.g., cooling afterthe temperature spike in a controlled process). This heat treatment,along with the composition of the present invention, results in adesired steel product with the same or similar properties as lead alloysteels, such as but not limited to having the desired machinability,wear resistance, hardenability, and dimensional stability, as well asresulting in prolonged tool life of the tools used to machine the steelproducts, desired machining speeds, feed rates, and productivity duringmanufacturing of machined components made from the steel productsdescribed herein. For example, the steels produced from the compositionand/or heat treatment described herein may results in small machiningchips. It may be desirable to create small chips during machining asopposed to long pieces of metal shavings. The long pieces of metalshavings may interfere with the machine tooling and/or the machinedcomponents, whereas small chips do not have the same interferenceissues.

The term “machinability”, as described herein, is a relative measure ofhow easily a material can be machined when compared to American Iron andSteel Institute (AISI) 1212 steel. In accordance with the AISIspecification, turning tests of AISI 1212 steel represent a 100% rating,if the material being compared has a turning test result that is lessthan 100% it is more difficult to machine, while a turning test resultthat exceeds 100% would be easier to machine. Based on the compositionand process of forming the steel product, including the heat treatment,the machinability of aspects of the present invention may be up to about86%, or greater than about 70%, greater than about 75%, greater thanabout 80%, greater than about 85%, greater than about 90%, or cover arange between any values anywhere in-between two or more of thesevalues, or values between these which are not specifically stated. Assuch, the steel products of the present invention may have the same orsimilar machinability as similar steels that include lead (e.g., 41L40,or other like leaded steels). It should be understood that the lead-freeor substantially lead-free steels described herein may have the same orsimilar machinability of leaded steels regardless of the machinabilityof the steels (e.g., regardless if they are above or below 100%machinability). That is, the comparison is made between themachinability of comparable lead-free and leaded steels.

The composition of the lead-free or substantially lead-free steels maybe defined by one or more elements described herein, and may be presentas controlled elements or as unavoidable impurities of the steel makingprocess (e.g., based on the scrap steel utilized, or the like), with theremaining portion of the steel material being iron (Fe). For example,Table 1 below lists potential elements for the steels of the presentinvention with one or more percent weight ranges. Additional ranges ofthese elements and the effect of at least some of these elements on thesteels of the present invention are described in further detail below.As illustrated in Table 1, the elements from carbon to oxygen may becontrolled, while the elements from Vanadium to Titanium may or may notbe controlled.

It should be understood that the term “about” may be added to thedescription of the values for the ranges of elements, temperatures,times, percentages, or the like discussed herein. As such, the term“about” is intended to encompass the measurement error associated withthe numerical value described thereafter (e.g., +/−1, 2, 3, 4, 5, 6, 7,8, 9, 10 unit, such as fraction of a percent, percent, or the like).Moreover, it should be understood that the ranges of a particularelement may be a combination of any values, or ranges of valuesdescribed for the particular element, or may be within, overlapping, oroutside of a particular range provided.

TABLE 1 Potential elements and potential ranges of each, which may becontrolled or may appear as unavoidable impurities. Preferred Range(wt-% Element unless stated otherwise) Other Range(s) (wt-%) Carbon (C)0.39 to 0.43  0.2 to 0.6 Manganese (Mn) 0.75 to 1.0   0.6 to 1.1 Silicon(Si) 0.15 to 0.35  0.1 to 0.4 Chromium (Cr)  0.8 to 1.05  0.6 to 1.2Molybdenum (Mo) 0.15 to 0.25  0.1 to 0.3 Tellurium (Te) 0.003 to 0.0900.001 to 0.12 Selenium (Se) 0.08 to 0.2   0.05 to 0.25 Sulfur (S) 0.065to 0.09   0.04 to 0.12 Bismuth (Bi) 0.03 to 0.1   0.01 to 0.15 Nitrogen(N) 1-100 ppm; 50-150 ppm 0.08 max; or 0.0001 to 0.08 Oxygen (O) 1 to 30ppm   0.005 max; or 0.0001 to 0.005 Vanadium (V) 0.01 max 0.02 max; 0.03max; or 0.0001 to 0.03 Phosphorus (P) 0.03 max 0.04 max; 0.05 max; or0.0001 to 0.05 Copper (Cu)  0.1 max 0.25 max; 0.5 max; or 0.0001 to 0.5Nickel (Ni)  0.2 max 0.3 max; 0.5 max; or 0.0001 to 0.5 Aluminum (Al)0.01 max 0.02 max; 0.04 max; or 0.0001 to 0.04 Niobium (Nb) 0.01 max0.02 max; 0.03 max; or 0.0001 to 0.04 Lead (Pb) 0.02 max 0.03 max; 0.05max; or 0.0001 to 0.05 Tin (Sn) 0.03 max 0.04 max; 0.06 max; or 0.0001to 0.06 Calcium (Ca) 0.002 max  0.005 max; 0.01 max; 0.00001 to 0.002Boron (B) 0.0005 max  0.001 max; 0.005 max; 0.0001 to 0.005 Titanium(Ti)  0.1 max 0.2 max; 0.3 max; 0.0001 to 0.3

Carbon added in certain amounts will improve the hardness of the steelproduct. Too high of an amount of carbon may, however, deteriorate themachinability. Therefore, the upper limit of carbon, when considered incombination with other elements in the steel should be about 0.2 wt-% toabout 0.6 wt-% to avoid a decrease of the machinability. The lower limitof carbon should be about 0.2 wt-%, 0.3 wt-% or 0.4 wt-%. In someaspects of the invention the carbon content may range from 0.39 wt-% to0.43 wt-%. Low carbon content is beneficial for the machinability, buthas a detrimental effect on other properties (e.g., becomes less hard,loses strength, and becomes more ductile). These detrimental effects canbe neutralized by adjusting amounts of alternative elements, for exampleMn, Te, Se, S, Bi, and/or other like elements, as described below.

Silicon has a solution hardening effect (e.g., strengthen the metal).Silicon also increases the carbon activity during heat treatment (e.g.,reaction between the Si and C). Moreover, due to its high affinity tooxygen, silicon is often used to deoxidize steel during manufacture inorder to improve the purity of the material. These effects are notavailable at a silicon content less than 0.1 wt-%. At high siliconcontents, the hot forming processability deteriorates. Therefore, insteels of the present disclosure the silicon content should not exceed0.4 wt-%. In some aspects of the invention the silicon content may rangefrom about 0.15 wt-% to about 0.35 wt-%.

Molybdenum increases the hardenability of the steel product. However, ahigh molybdenum content might impair the hot workability of the steel.As such, the upper limit for molybdenum should be 0.3 wt-% in the steelof the present disclosure, preferably maximally 0.25 wt-%. In someaspects of the invention the molybdenum may range from about 0.15-0.25wt-%.

Tellurium (Te), selenium (Se), Sulfur (S), Bismuth (Bi), and/or otherlike elements increase the machinability of the steel.

With respect to Tellurium (Te), it reacts with manganese to formmanganese telluride in the solid steel product and has a similar effectas adding lead. It also acts to modify the shape of manganese sulphideinclusions from elongated to a globular morphology. The Te content inthe present composition that achieves the improvements described hereinand permits the heat treatment described herein to result in the removalof scale using traditional methods, may range from 0.001 to 0.12 wt-%,and preferably may range from 0.003-0.090 wt-%.

With respect to Selenium (Se), this addition modifies the shape ofmanganese sulphide inclusions enhancing machinability. The Se content inthe present composition that achieves the improvements described herein,and allows for the heat treatment described herein to result in theremoval of scale using traditional methods, may range from 0.05 to 0.25wt-%, and preferably may range from 0.08 to 0.2 wt-%.

With respect to Sulfur (S), this addition forms with other elements tocreate sulphides (e.g. manganese sulphides, or the like). Sulphidesreadily undergo plastic deformation during rolling, forging or coldworking (e.g., cold drawing, or the like), and increased sulphidesresult in drastically reducing tool wear during machining. The sulfurcontent in the present composition that achieves the improvementsdescribed herein, and permits for the heat treatment described herein toresult in the removal of scale using traditional methods, is elevatedcompared to sulfur levels in other types of steels (e.g., 41L40 steel),such as 0.04 wt-% or more, preferably at least 0.05 wt-%, morepreferably in a range of about 0.065 wt-% to about 0.090 wt-%.Therefore, the sulfur content should be minimally 0.04 wt-% andmaximally 0.12 wt-%.

With respect to Bismuth (Bi), this forms discrete particles in the steelstructure on solidification, often present as tails on manganesesulphide inclusions. During machining, the Bi melts locally at thetool-steel product workpiece interface acting as a lubricant andreducing tool wear. The Bi content in the present composition thatachieves the improvements described herein, and allows for the heattreatment described herein to result in the removal of scale usingtraditional methods, may range from 0.01 to 0.15 wt-%, and preferablymay range from 0.03 to 0.1 wt-%.

Manganese influences the morphology of the sulphides. Mn in combinationwith Te, Se, S, and/or Bi enhances the size and shape of the MnSinclusions leading to improved machinability. Manganese also leads to atendency of increased work hardening and higher hardenability. Largeamounts of manganese in a free-cutting steel can, however, reduce thecorrosion resistance. In combination with the sulfur, a manganesecontent less than about 0.7 wt-% would lead to an insufficient amount ofsulphides, while an excess amount of manganese, more than 1.1 wt-%,results in an increased tendency of work hardening, which in turn leadsto decreased machinability. Preferably, the Mn content is about 0.6-1.1wt-%, more preferably 0.75-1.0 wt-%.

Chromium is an element that improves the hardenability and corrosionresistance. In the present disclosure, the chromium content should bemaximally about 1.1 wt-% to avoid any negative effects on the propertiesof the material (e.g., too hard for desired machinability). Preferably,the chromium content should be 0.7-1.1 wt-%, more preferably 0.8-1.05wt-%.

The previously recited elements discussed above may be controlled to theillustrated ranges. The following elements discussed below may also becontrolled in some aspects of the invention. However, in other aspectsof the invention the following elements may appear as impurities withinthe steel because they are a part of the scrap steel utilized to createthe steel of the present invention.

Boron enhances the hardenability of the steel, and also in small amountsimproves the hot workability. However, formation of boron nitrides issometimes considered to cause increased tool wear due to the relativelyhigh hardness of the formed inclusions. Boron in excessive amounts isalso generally considered to cause poor hot ductility of the material.Consequently, the boron content may be maximally 0.008 wt-% in thesteel, preferably maximally 0.0010 wt-%, or 0.0005 wt-%. In some aspectsof the invention the boron may be added and controlled, but in otheraspects the boron exists as a trace element from the boron in the scrapsteel, which may or may not be controlled.

Copper may provide a positive effect on the machinability in regards totool lifetime, such as at turning. Copper may provide improved corrosionproperties, and in particular it may reduce the rate of generalcorrosion. However, if added in an amount that is too high, copper maylower the hot ductility of the material and deteriorate the ability tocreate small chips during machining. As previously discussed, smallchips may be desirable to prevent long pieces of metal shavings frominterfering with the machine tooling and/or the machined components.Copper may therefore be present in scrap steel in an amount of up to 2.0wt-%. According to some aspects of the invention, the alloy may containup to 0.35 wt-% copper. However, it may be advantageous to limit thecopper to 0.25 wt-% max, or 0.1 wt-% max in some aspects. In someaspects of the invention, the copper may be added and controlled, but inother aspects the copper exists as trace elements from the copper in thescrap steel, which may or may not be controlled.

Nickel may be present in small amounts in scrap steel or may be added,and may or may not be controlled. Nickel does not have a substantialeffect on machinability, but it may be used to increase strength,improve wearability, and/or improve corrosion resistance. Due to highcosts for nickel alloys, the nickel content normally in scrap steel maybe below 1 wt-%, preferably maximally 0.5 wt-%, more preferablymaximally 0.2 wt-%.

Titanium content should be as low as possible to avoid formation ofinclusions of titanium nitrides or carbides. These inclusions are veryhard and will lead to increased tool wear. Hence, the titanium contentshould be as low as possible. As such, titanium may be kept to 0.2 wt-%max, more preferably 0.1 wt-% max, 0.05 wt-% max, or the like.

Vanadium combines with nitrogen and carbon to form nitrides andcarbides, which prevents grain growth (e.g., reduce grain size) in thesteel. However, vanadium nitrides and/or carbides have the same effectas titanium nitrides and/or carbides on the tool wear, which means thatthe vanadium content should also be as low as possible. As such,Vanadium may be kept to 0.03 wt-% max, or more preferably 0.01 wt-% max,0.005 wt-% max, or the like.

Niobium normally is useful to prevent coarsening of the crystal grainsin the steel at high temperature, but endogenously formed niobiumnitrides will have a detrimental effect on the machinability.Consequently, the niobium content should be kept as low as possible. Assuch, niobium may be kept to 0.03 wt-% max, or more preferably 0.01 wt-%max, 0.005 wt-% max, or the like.

To avoid negative effects on the machinability, the sum of the titanium,niobium, vanadium, and/or zirconium additions (or trace amounts from thescrap steel) may be maximally 0.3 wt-%, or more preferably 0.2 wt-%. Insome aspects of the invention, other than present as trace impuritiesdue to the nature of the scrap steel, the present composition is freefrom additions of titanium, niobium, zirconium and vanadium.

The steel product may also contain normally occurring impurities due tothe raw material used, scrap steel used, and/or the manufacturingprocess selected. The content of these impurities may be included (or insome aspects controlled) such that the properties of the produced steelare substantially unaffected by the presence of these impurities. Oneexample of such an impurity is nitrogen which is suitably kept below0.08 wt-%. In some aspects of the invention the nitrogen content may bebetween 50-150 ppm. Other examples are phosphorous, aluminum, and/orother elements that may or may not be illustrated in Table 1, theamounts thereof may or may not be carefully monitored.

With respect to the heat treatment process (e.g., annealing process) ofthe present disclosure, in some aspects, heating and/or cooling of thesteel product in accordance with the methods described herein can beperformed using a non-ambient atmosphere, such as >99% nitrogen, or canbe a mixture of gases (e.g., mixture of nitrogen, propylene, oxygen, orthe like). In some aspects of the invention, heating and/or cooling ofthe steel product in accordance with the methods described herein can beperformed using a mixture of nitrogen and one or more hydrocarbons. Insome aspects of the invention, heating and/or cooling of the steelproducts in accordance with the methods described herein can beperformed using a mixture of nitrogen, oxygen, and one or morehydrocarbons. For example, heating and/or cooling of the steel productin accordance with the annealing process described herein can beperformed using a mixture of nitrogen, oxygen, and ethane and/orpropane. Inert gases, such as argon, krypton, or neon can be mixed oradded to the atmosphere during the heating/cooling method.

In some aspects of the invention, the method of improving themachinability of an essentially lead free steel comprises subjecting asteel product to a first heat treatment at a first temperature (e.g.,1500-1800 degrees F., or 1590-1690 degrees F.) for a first time period,and subsequently subjecting the product to a second heat treatment, thesecond heat treatment occurring at a second temperature (e.g., 1000-1300degrees F., or 1100-1200 degrees F.) lower than the first temperaturefor a second time period. The method further comprises, subsequent tothe duration of the second time period, subjecting the steel product toa third heat treatment at a third temperature (e.g., 1100-1400 degreesF., or 1200-1300 degrees F.) higher than the second temperature for athird period (e.g., heating the product back up, such as in atemperature spike, and/or holding the steel product at a thirdtemperature). The method further comprises, subsequent to the durationof the third time period, subjecting the steel product to a furnace cool(e.g., shutting off the heat and allowing the product to cool,controlled cooling, or the like). It should be understood that any ofthese time periods may include one or more sub-time periods during whichthe steel product is heated or cooled at one or more temperatures.

In some aspects of the invention, the steel products may be heated up toa first temperature above the austenitizing range over a desired span oftime in one or more process steps and held at the first temperature fora desired duration. As such, the steel products may be heated up untilthey have a microstructure in the austenitic phase. Thereafter, thetemperature of the steel products may be lowered from above theaustenitizing range to below the austenitizing range over a desired spanof time in one or more process steps and held at a second temperaturefor a desired span of time. At this second temperature the steelproducts may be in the pearlitic/ferritic phase. Thereafter, thetemperature of the steel products may be increased while staying in thepearlitic/ferritic phase over a desired time period, and held at thisthird temperature for a desired span of time (e.g., a rapid temperaturespike, or the like). In some aspects of the invention, this increase intemperature may be a sharp rise in temperature over a short span of time(e.g., approximately a 50 to 125 degree increase over 5 to 12 minutes,or the like). Finally, the temperature of the steel products may belowered over a desired span of time to cool the steel product as afinishing step of the heat treatment. It should be noted that each stepmay contain one or more steps including different temperatures and timesat those temperatures to achieve proper physical and microstructuralresults.

In some aspect discussed below (e.g., with respect to the samplespecimens as discussed below), the steel product may be subjected theheat treatments, or portions thereof, illustrated in Tables 2 or 3 attemperatures and for durations which fall within the recited ranges.

TABLE 2 Heat Treatment Segment Temperature and Duration Ranges EndInitial SetPoint Segment SetPoint (° F.) (° F.) Time (hr:mins)Atmosphere 1 0  900-1200 15 to 45 mins. N2, Propylene, O2 2  900-12001050-1350 2.5 to 3.5 hr. N2, Propane, O2 3 1050-1350 1500-1800 15 to 45mins. N2, Propane, O2 4 1500-1800 1500-1800 1 to 2 hr. N2, Propane, O2 51500-1800 1425-1725 20 to 60 mins N2, Propane, O2 MV 6 1425-17251425-1725 15 to 45 mins N2, Propane, O2 7 1425-1725 1425-1725 1 to 2 hr.N2, Propane, O2 8 1425-1725 1000-1300 1.5 to 2.5 hr. N2, Propane Off 91000-1300 1000-1300 35 to 75 mins N2, Propane Off 10 1000-1300 1000-13001 to 10 mins N2, Propane Off 11 1000-1300 1100-1400 1 to 20 mins N2,Propane Off 12 1100-1400 1100-1400 45 to 75 mins N2, Propane Off 131100-1400  50-350 15 to 45 mins N2, Propane Off 14  50-350  1-50 END

As shown in Tables 2 and 3, in one aspect the method comprisessubjecting a steel product to a first heat schedule as shown in segments1-4 for a first time period and subsequently subjecting the steelproduct to a second heat schedule of a temperature lower than the firstheat for a second time period, as shown in segments 5-7. The methodfurther comprises, subsequent to the duration of the second time period,as shown in segments 8-10, subjecting the steel product to a third heatschedule of a temperature less than the second heat schedule for a thirdperiod. The method further comprises, subsequent to the duration of thethird time period, as shown in segments 11-12, subjecting the steelproduct to a fourth heat schedule of a temperature greater than thethird heat for a fourth period. The method further comprises, as shownin segment 13, subsequent to the duration of the fourth time period,subjecting the steel product to cooling. In addition to the rangesillustrated in Tables 2 and 3 the temperatures for segments 1-5 can beheld to a +0/−50 F deviation. The heat temperatures for segment 6 can beheld to a +0/−25 F deviation. The heat temperatures for segment 7 can beheld to a +0/−50 F deviation. In still other aspects of the invention,in addition to the ranges illustrated for the temperatures in Tables 2and 3, the deviation for any one of the values within the range may be+/−10, 20, 30, 40, or 50 degrees F. Moreover, with respect to the timedurations illustrated for each of the segments, the deviations of theranges, or values within may be held to +/−10, 20, 30, 40, 50, or 60mins.

TABLE 3 Heat Treatment Segments and Duration Ranges Initial End SetPointSetPoint Time Segment (° F.) (° F.) (hr:mins) Atmosphere 1  0 1020-10600:20-0:40 N2, Propylene, O2 2 1020-1060 1170-1210 2:30-3:30 N2, Propane,O2 3 1170-1210 1610-1650 0:20-0:40 N2, Propane, O2 4 1610-1650 1610-16501:10-1:50 N2, Propane, O2 5 1610-1650 1550-1590 0:30-0:50 N2, Propane,O2 6 1550-1590 1550-1590 0:20-0:40 N2, Propane, O2 7 1550-1590 1550-15901:10-1:50 N2, Propane, O2 8 1550-1590 1120-1160 1:40-2:20 N2, PropaneOff 9 1120-1160 1120-1160 0:40-1:10 N2, Propane Off 10 1120-11601120-1160 0:01-0:10 N2, Propane Off 11 1120-1160 1220-1260 0:05-0:15 N2,Propane Off 12 1220-1260 1220-1260 0:45-1:15 N2, Propane Off 131220-1260 170-210 0:20-0:40 N2, Propane Off 14 200 20-60 END

In some aspects of the invention steel samples were made in which thecomposition included approximately C: 0.39-0.43 wt-%; Mn: 0.75-1.0 wt-%;Si: 0.15-0.35%; Cr: 0.80-1.05; Mo: 0.15-0.25; and one or more of Te:0.003-0.090 wt-%; Se: 0.080-0.200 wt-%; S: 0.065-0.09 wt-%; Bi:0.030-0.100 wt-%; and balance being Fe and normally occurring scrapsteel impurities.

Sample alloys were produced in an EAF by melting scrap steel withsubsequent alloying addition at the Ladle Metallurgy Furnace and castinginto billets. The billets were then placed in a reheat furnace to bringthem to a desired temperature (e.g., 1700 to 2500 degrees F., or anotherlike range that is inside, overlapping, or outside of this range) over adesired time (e.g., 30 mins to 5 hours, or another like range inside,overlapping, or outside of this range). After reheating, the sampleswere taken from the furnace at the desired temperature (e.g., 1700 to2500 degrees F., or in another like range inside, overlapping, oroutside of this range) for rolling, and/or other steps. The samples weremade with roughing, breakdown, and/or finishing steps, with multiplerolling stands included in each step according to reduction requirementsbased on the desired size of the finished steel product samples (e.g.,bar product diameter, or the like). The steel product samples wererolled into straight bars. In other aspects of the invention, the steelproducts may be straight bars or rolled into coils as required forfurther processing steps. Once the steel product samples were rolled tothe desired size and shape they were cut to the desired length andsubjected to the heat treatments described in Tables 2 and 3 discussedabove. The heat treatment, including the heating and cooling segmentstages discussed herein, can include multiple steps and temperatures inorder to allow the steel products meet the physical and dimensionalrequirements (e.g., Tables 2 and 3). After heat treatment the steelproduct samples were subjected to a cold drawing process during whichthey were formed into the desired steel product shape. The steel productsamples were then machined and tested verses comparable steels, such as41L40 steels.

The samples of the steel products made according to the compositions andthe processing, including the heat treatment, described herein, did notillustrate any deficiency in machinability, tool life, machining speed,machining feed rates, or machining productivity when being machined intomachined products, when compared to steel compositions that utilize leadand are formed using traditional processing. The steels of the presentinvention included the additions, and/or increases, of Te, Se, S, Bi,and/or other elements described herein, and were formed utilizing theheat treatment described herein. As such, the steel of the presentinvention that are free, or are substantially-free, of lead are at leastas good, if not superior to, comparable leaded steels, such as the 41L40steel, or other like leaded steel grades.

Investigations of the microstructures of the steel product sampleshaving the compositions and heat treatment described herein, andcertified to ASTM A-108 cold finishing dimensional requirements, showeda mostly lamellar perlite microstructure after the heat treatment. Thesamples prepared in accordance with the compositions and methodsdisclosed herein showed at least a 50% lamellar perlite microstructure,at least a 60% lamellar perlite microstructure, at least a 70% lamellarperlite microstructure, at least a 75% (or about 70-80%, or the like)lamellar perlite microstructure, or at least a 85% (or about 85 to 90%,or the like) lamellar perlite microstructure after the heat treatment.It should be understood that the ranges of the lamellar perlitemicrostructure of the steels produced using the compositions and heattreatment described herein may be within, outside, and/or overlappingany of the ranges or two or more of the values described herein.

The heat treatment performed on the steel products discussed herein willchange the microstructure and physical properties of the steel products.The steel products may have a softer and more ductile microstructurewhen compared to steels formed without a heat treatment. The yield andtensile strength of the steel products will decrease, while theelongation and reduction of area properties will increase after heattreatment when compared to steels without a heat treatment. Theannealing process softens the steel products with the result that itincreases the life of the dies used in the cold working (e.g., colddrawing, cold rolling, or cold extrusion process). Cold working will inturn increase the yield and tensile strength, and lower the elongationand reduction of the cross-sectional area of the steel products. Theyield and tensile strength after cold drawing will increase, but not tothe levels that could have been achieved prior to heat treatment. Theelongation and reduction of the cross-sectional area will decrease, butwill be higher than prior to heat treatment. The finished product afterheat treatment and cold drawing will have physical and microstructuralproperties (e.g., as described below) that enhance machinability whilekeeping the physical properties such as yield strength, tensilestrength, % elongation, and % reduction of cross-sectional area at thesame or similar acceptable levels when compared to similar steels, suchas but not limited to 41L40 type steels.

Examples of the microstructure of one of the samples are illustrated inFIGS. 2-5. FIG. 2 illustrates 500× magnification of a longitudinally cutsample of the steel discussed herein in the hot rolled and annealedcondition near the core the bar. FIG. 2 illustrates the predominantlylamellar pearlitic microstructure with ferrite bands in the rollingdirection. FIG. 3 illustrates 500× magnification of a longitudinally cutsample of the steel discussed herein in the hot rolled and annealedcondition near the surface of the bar. FIG. 3 illustrates thepredominantly lamellar pearlitic microstructure (i.e., darker areas)with ferritic microstructure interspersed (e.g., lighter areas). FIG. 4illustrates 500× magnification of a transverse cut sample of the steeldiscussed herein in the hot rolled and annealed condition near the coreof the bar. FIG. 4 illustrates the predominantly lamellar pearliticmicrostructure with ferritic microstructure. FIG. 5 illustrates 500×magnification of a transverse cut sample in the hot rolled and annealedcondition near the surface of the bar. FIG. 5 illustrates thepredominantly lamellar pearlitic microstructure with ferritic grainsthroughout.

The results of the machining tests of the sample steel products indicatethat the addition of, and/or the elevated amounts of, Te, Se, S, and/orBi have a beneficial effect on machinability and hardenability whencompared to steel products that do not use, or have amounts of theseelements outside of the ranges discussed herein. For example, asdescribed herein, the addition of, or the increased amount of, Te, Se,S, or Bi when compared to conventional amounts of these elements, allowsthe steel product to have the desired machinability and/or hardness whencompared with similar steels containing lead.

Additionally, the present composition, in combination with the heattreatment provides additional manufacturing benefits and advantages. Forexample, because of the addition of, or the increased amount of, Te, Se,S, Bi, or the like in place of lead, scaling of the product is moreadherent to the steel products when compared to steel products withoutor with lower amounts of Te, Se, S, Bi, and/or other elements. However,the various aspects of the heat treatment disclosed herein make thescaling less adherent to the steel product and consequently, the steelproduct is easier to descale. As such, the heat treatment provides forthe ability to add, and/or utilize higher levels of, Te, Se, S, Bi, orother components in the steel products to improve machinability (e.g.,on par or better than steels that use lead), and maintain the use oftraditional scaling removal processes (e.g., sand blasting, shotblasting, or the like) to remove scaling from the steel products of thepresent invention.

The increase in machinability without using lead is dependent on the useof, or the increased amounts of, one or more of the Te, Se, S, Bi, orother elements in the composition of the steel in the present invention,either alone, or in combination with, the heat treatment processingdescribed herein. The present disclosure improves the machinability ofthe material, without the need for lead (or with only trace elements oflead from scrap steel) and without detriment of the other materialproperties of the steel (e.g., comparable or the same as the 41L40steel, or other like similar steel grades). For example, themachinability, as previously described may be up to or above about 75%,80%, 85%, 86%, or the like, or within or overlapping any ranges orvalues thereof. Moreover, the wear resistance and corrosion resistanceof the end product is the same as or similar to comparable leadedproducts.

The steel according to the present disclosure can be produced byconventional melting processes, such as in a Blast Furnace, Electric ArcFurnace, or the like. However, it should be understood that the steelproducts of the present invention may be made utilizing any type ofsteel manufacturing process, and the same benefits may be achieved.

While certain exemplary aspects have been described and shown in theaccompanying drawings, it is to be understood that such aspects aremerely illustrative of and not restrictive on the broad invention, andthat this invention not be limited to the specific constructions andarrangements shown and described, since various other changes,combinations, omissions, modifications and substitutions, in addition tothose set forth in the above paragraphs, are possible. Those skilled inthe art will appreciate that various adaptations, modifications, andcombinations of the just described aspects of the invention can beconfigured without departing from the scope and spirit of the invention.Therefore, it is to be understood that, within the scope of the appendedclaims, the invention may be practiced other than as specificallydescribed herein.

Also, it will be understood that, where possible, any of the advantages,features, functions, devices, and/or operation of any of the aspects ofthe present invention described and/or contemplated herein may beincluded in any of the other aspects of the present invention describedand/or contemplated herein, and/or vice versa. In addition, wherepossible, any terms expressed in the singular form herein are meant toalso include the plural form and/or vice versa, unless explicitly statedotherwise. Accordingly, the terms “a” and/or “an” shall mean “one ormore.”

What is claimed is:
 1. A steel product that is essentially lead free,wherein the steel product comprises: carbon in a range of 0.2 to 0.6wt-%; manganese in a range of 0.6 to 1.1 wt-%; silicon in a range of 0.1to 0.4 wt-%; chromium in a range of 0.6 to 1.2 wt-%; molybdenum in arange of 0.1 to 0.3 wt-%; at least one or more of: tellurium in a rangeof 0.001 to 0.12 wt-%; selenium in a range of 0.05 to 0.25 wt-%; sulfurin a range of 0.4 to 0.12 wt-%; or bismuth in a range of 0.01 to 0.15wt-%; balance being Fe and normally occurring scrap steel impurities;and wherein the steel product is subjected to a heat treatment processduring which the steel product is subjected to: a first temperature fora first duration; a second temperature for a second duration, whereinthe second temperature is less than the first temperature; a thirdtemperature for a for a third time period, wherein the third temperatureis greater than the second temperature; and cooled after the thirdtemperature.
 2. The steel product of claim 1, wherein the compositioncomprises only the tellurium, and wherein the tellurium is in a range of0.003 to 0.090 wt-%.
 3. The steel product of claim 1, wherein thecomposition comprises only the selenium, and wherein the selenium is ina range of 0.080 to 0.20 wt-%.
 4. The steel product of claim 1, whereinthe composition comprises only the sulfur, and wherein the sulfur is ina range of 0.065 to 0.090 wt-%.
 5. The steel product of claim 1, whereinthe composition comprises only the bismuth, and wherein the bismuth isin a range of 0.03 to 0.1 wt-%.
 6. The steel product of claim 1, whereinat the first temperature the steel product is in an austenitic phase,wherein at the second temperature and the third temperature the steelproduct is in a pearlitic/ferritic phase.
 7. The steel product of claim1, wherein the first temperature ranges between 1500-1800 degrees F.,the second temperature ranges between 1000-1300 degrees F., and thethird temperature ranges between 1100-1400 degrees F.
 8. The steelproduct of claim 7, wherein the first temperature ranges between1590-1690 degrees F., the second temperature ranges between 1100-1200degrees F., and the third temperature ranges between 1200-1300 degreesF.
 9. The steel product of claim 1, wherein a microstructure of thesteel product comprises lamellar perlite.
 10. The steel of claim 9,wherein the microstructure comprises at least 75% lamellar perlite. 11.A method for manufacturing an essentially lead free steel, the methodcomprising: subjecting a hot rolled steel product to a heat treatment inwhich the steel product is subjected to a first temperature for a firstduration; the steel product is subjected to a second temperature for asecond duration, wherein the second temperature is less than the firsttemperature; and the steel product is subjected to a third temperaturefor a third time period, wherein the third temperature is greater thanthe second temperature; cooling the steel product; and wherein the steelproduct comprises the following composition: carbon in a range of 0.2 to0.6 wt-%; manganese in a range of 0.6 to 1.1 wt-%; silicon in a range of0.1 to 0.4 wt-%; chromium in a range of 0.6 to 1.2 wt-%; molybdenum in arange of 0.1 to 0.3 wt-%; at least one or more of: tellurium in a rangeof 0.001 to 0.12 wt-%; selenium in a range of 0.05 to 0.25 wt-%; sulfurin a range of 0.4 to 0.12 wt-%; or bismuth in a range of 0.01 to 0.15wt-%; and balance being Fe and normally occurring scrap steelimpurities.
 12. The method of claim 11, wherein the compositioncomprises only the tellurium, and wherein the tellurium is in a range of0.003 to 0.090 wt-%.
 13. The method of claim 11, wherein the compositioncomprises only the selenium, and wherein the selenium is in a range of0.080 to 0.20 wt-%.
 14. The method of claim 11, wherein the compositioncomprises only the sulfur, and wherein the sulfur is in a range of 0.065to 0.090 wt-%.
 15. The method of claim 11, wherein the compositioncomprises only the bismuth, and wherein the bismuth is in a range of0.03 to 0.1 wt-%.
 16. The method of claim 11, wherein at the firsttemperature the steel product is in an austenitic phase, wherein at thesecond temperature and the third temperature the steel product is in apearlitic/ferritic phase, and wherein in at the third temperature isgreater than the second temperature.
 17. The method of claim 11, whereinthe first temperature ranges between 1500-1800 degrees F., the secondtemperature ranges between 1000-1300 degrees F., and the thirdtemperature ranges between 1100-1400 degrees F.
 18. The method of claim17, wherein the first temperature ranges between 1590-1690 degrees F.,the second temperature ranges between 1100-1200 degrees F., and thethird temperature ranges between 1200-1300 degrees F.
 19. The method ofclaim 11, wherein a microstructure of the steel product compriseslamellar perlite.
 20. The method of claim 19, wherein the microstructurecomprises at least 75% lamellar perlite.
 21. A steel product that isessentially lead free, wherein the steel product comprises: carbon in arange of 0.2 to 0.6 wt-%; manganese in a range of 0.6 to 1.1 wt-%;silicon in a range of 0.1 to 0.4 wt-%; chromium in a range of 0.6 to 1.2wt-%; molybdenum in a range of 0.1 to 0.3 wt-%; at least one or more of:tellurium in a range of 0.001 to 0.12 wt-%; selenium in a range of 0.05to 0.25 wt-%; sulfur in a range of 0.4 to 0.12 wt-%; or bismuth in arange of 0.01 to 0.15 wt-%; balance being Fe and normally occurringscrap steel impurities.
 22. A method for a heat treatment process, themethod comprising: subjecting a hot rolled steel product to a heattreatment in which the steel product is subjected to a first temperaturefor a first duration, wherein the first temperature ranges between1500-1800 degrees F.; the steel product is subjected to a secondtemperature for a second duration, wherein the second temperature rangesbetween 1000-1300 degrees F., and wherein the second temperature is lessthan the first temperature; and the steel product is subjected to athird temperature for a third time period, wherein the third temperatureranges between 1100-1400 degrees F., and wherein the third temperatureis greater than the second temperature; and cooling the steel product.